A major part of our work has been studying the cellular basis of pain sensation. Initially, we have concentrated on trigeminal and dorsal root ganglion neurons expressing the TrpV1 ion channel. We have been using a variety of pharmocological and molecular genetic techniques to explore the molecular architecture of these neurons and their sensitivity to drugs and other stimuli. In this reporting period we have shown that molecularly defined subsets of these cells are involved in different aspects of nociception. These neurons are also involved in detection of other classes of stimuli and we have determined they have plastic changes in their structure. Screens of molecules expressed in soamtosensory neurons have revealed a number of novel signaling molecules and at present we are studying their physiological role. In addition we have embarked on projects aimed at determining the molecular expression patterns of touch sensitive neurons.